<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta http-equiv="X-UA-Compatible" content="IE=edge">
	<title></title>
	<link rel="stylesheet" href="">
</head>
<body>
<!-- <script src="https://cdn.bootcss.com/vue/2.5.8/vue.js"></script> -->
<script src='http://cdn.jsdelivr.net/vue/1.0.26/vue.js'></script>
<div id="root">
	{{b}}-{{a.c}}
</div>
<script>
	var vm = new Vue({
		el : '#root',
		data : {
			a : 1,
			b : 2,
		}
	});
	vm.$watch('a',()=>console.log('哈哈，$watch成功了'));
	setTimeout(()=>{vm.a={c : 4}},3000);
</script>	
</body>
</html>